1. Field of the Invention
The present invention relates to a feeding device for shredder dust for performing an incinerating process by burning shredder dust comprising various shredded waste materials by feeding the shredder dust to a furnace such as a reverberatory furnace for non-ferrous smelting and to a furnace provided with this feeding device.
2. Description of the Related Art
In recent years the processing of industrial waste materials has become a problem for society. Currently, the landfilling of waste materials is severely restricted and incineration methods are also regulated so as to prevent dioxin from being generated. In this situation, in order to recover various metals such as copper, gold, silver, and, palladium without generating dioxin, the inventors of the present invention attempted the processing of automobile shredder dust in a reverberatory furnace. Here, the term shredder dust is used to refer generally to fluff materials coming out when scrapped vehicles are crushed in order to recover steel and aluminum. Shredder dust is more easily burnt than chipped tires and also contains valuable metals; therefore, the processing ratio of such attempts is continually improving.
A schematic flow chart of the processing of automobile shredder dust in a reverberatory furnace is shown in FIG. 16. In this flow chart, the reverberatory furnace 1 is a green charge type (wet charge type) reverberatory furnace used for non-ferrous smelting and in particular for smelting copper concentrates. Industrial waste materials such as automobil shredder dust are stored in the stockyard 2, then transported to the reverberatory furnace 1 by conveyors 4 from the feed hopper 3 and fed into the inside of the reverberatory furnace 1 through a feeding chute composed by such as a steel pipe. The industrial waste materials are then processing in the reverberatory furnace 1 together with copper concentrates. Oxygen enriched air is also supplied to the reverberatory furnace 1 from an oxygen plant 5.
Moreover, the off-gas from the reverberatory furnace 1 is cooled through a waste heat boiler 6 for recovering heat and, then the dust in the off-gas has been collected by an electrostatic precipitator 7, SO2 in the gas is fixed as gypsum by a gypsum plant 8. Note that the steam generated in the waste heat boiler 6 is used to generate electrical power in a turbine generator 9, however, the amount of generated power corresponds to approximately half of the total amount of power consumption at the smelter. On the other hand, in the period when the converter is operating, dried copper concentrates and oxygen from the oxygen plant 5 are fed into the converter 10 and the off-gas is fed to the sulfuric acid plant 13 via the boiler 11 and the electrostatic precipitator 12. Moreover, an anode produced from the converter 10 via an anode furnace 14 is refined to electrolytic copper in a tank house (electro-refining plant) 15. In this tank house 15, gold, silver, and palladium are collected in anode slime.
As the present inventors were continuing the above described attempts, they noticed that there were several problems that needed to be resolved arising from the burning of shredder dust in the reverberatory furnace 1 in the above described manner. One of these problems was that the amount of shredder dust to be processed in the reverberatory furnace 1 was limited by the volume of off-gas expelled from the reverberatory furnace 1. Namely, if the atmosphere inside the reverberatory furnace 1 becomes insufficient in oxygen due to the off-gas generated in the burning of the shredder dust previously supplied or to the burning off-gases caused by fuel directly fed from the burner into the reverberatory furnace 1 and burnt therein, then even if new shredder dust is fed into the reverberatory furnace 1, this cannot be easily burnt and simply accumulates in an unprocessed state inside the reverberatory furnace 1.
Moreover, as described above, the shredder dust is stored the stockyard 2 of the smelter, transported by the conveyor 4 from the feed hopper 3, then fed to the inside of the reverberatory furnace 1 via a feeding chute. However, for example, if the feeding chute is simply installed in the ceiling of the reverberatory furnace 1 and the shredder dust simply fed into this chute, the off-gases increase and in cases in which it is not possible to maintain a sufficient negative draft inside the reverberatory furnace 1, there is the concern that the gas inside the furnace will leak out by the feeding chute. Since the ceiling needs to be so secure that the gas inside the furnace does not leak even when the shredder dust is being fed, it is necessary to provide a double-damper, for example, which results, of course, in the operation of feeding the shredder dust becoming complicated, but also means that continuous feeding is difficult. The ultimate result is that restrictions are placed on the amount of shredder dust that can be processed.
Another problem is that if shredder dust remains as unburnt condition when the shredder dust is charged to the reverberatory furnace 1, this unburnt shredder dust piles up in the reverberatory furnace 1 forming small hills (piles) in the furnace. If the dimension of these piles increases, the clearance between them and the ceiling of the reverberatory furnace 1 becomes smaller. As a result, when new shredder dust is fed to the top of the pile, the hot-gas goes out of the reverberatory furnace 1 through the feeding chute positioned directly above the pile, creating the concern that the conveyor belt used for transporting the shredder dust may be burnt. Moreover, particularly if these large piles are formed nearby the burners inside the reverberatory furnace 1, then the burning condition of the burners is disturbed which naturally results in the burning of the shredder dust not being possible, and also results in the burner combustion heat not being able to be used effectively for melting copper concentrates.
The present invention was achieved on the basis of these circumstances and it is an object thereof to provide an device for feeding shredder dust to a reverberatory furnace capable of securing the sealing of a feeding chute when shredder dust is fed to a reverberatory furnace used for non-ferrous smelting as described above and for ensuring that the shredder dust is burnt properly and thereby achieving an increase in the amount of this processing that can be performed.
In addition, a further aim of the present invention is to provide a furnace such as a reverberatory furnace in which the formation of large piles in the reverberatory furnace caused by unburnt of shredder dust is prevented, and in which the blocking of the propagation of combustion heat from the burner is prevented, and also in which hot gas is prevented from leaking out of the furnace.
In order to solve the above problems and achieve these objects, the structure described below has been employed in the present invention. Namely, the present invention relates to the device for feeding shredder dust to a reverberatory furnace through which shredder dust is fed to a reverberatory furnace for non-ferrous smelting, and in particular, to a device for feeding shredder dust to a reverberatory furnace in which a feeding chute that passes to the inside of the reverberatory furnace is fitted to the ceiling of the reverberatory furnace and shredder dust can be fed from this feeding chute, and which also allows oxygen enriched air to be supplied to the feeding chute and fed to the inside of the reverberatory furnace.
In this case, the feeding chute is branched partway along its length and it is desirable that the shredder dust is fed from one end thereof while the oxygen enriched air is supplied in from the other end thereof.
It is also desirable that an air supply nozzle that has a smaller diameter than the feeding chute is inserted in the other end of the branched feeding pipe and the distal end of the air supply nozzle is positioned adjacent to the branched portion of the feeding chute and that the oxygen enriched air is supplied in from the air supply nozzle.
Furthermore, the present invention relates to a reverberatory furnace for non-ferrous smelting provided with the shredder dust feeding device, and in particular, to a reverberatory furnace for non-ferrous smelting in which a burner is able to be installed in a wall portion of one end side thereof and a plurality of feeding ports to which are connected the feeding chutes of the shredder dust feeding device are provided at the one end side at a ceiling portion forming a plurality of staggered rows facing another end side.
In this case, it is desirable that, in the ceiling portion, the one end side where the feeding ports are provided is raised above the other end side.
Moreover, it is desirable that a feeding chute of the feeding device is connected to each one of the plurality of feeding ports and the positions at which shredder dust is fed to the feeding hoppers are arranged in a single row.
The second aspect of the present invention relates to a furnace for burning shredder dust which comprises: a furnace body; a burner provided on the wall on one side of the furnace body that emits a flame to the interior of the furnace body; one or a plurality of a raw material feeding openings provided on the side of the ceiling on the one side for feeding the raw material to be smelted to the interior of the furnace body; one or a plurality of a fuel and oxidizing gas feeding openings provided at the center of the ceiling on the one side; a main feeding chute installed in the fuel and oxidizing gas feeding opening; a first feeding chute installed inside the main feeding chute that feeds a compressed oxidizing gas to the furnace body; and a dust feeding chute that is connected to the main feeding chute and feeds shredder dust in the interior of the furnace body via the fuel and oxidizing gas feeding opening. A second feeding chute that feeds compressed oxidizing gas into the main feeding chute is installed vertically as a combustion device for the shredder dust; and the second feeding chute is installed such that the distal end thereof blows oxidizing gas to the shredder dust falling into the interior of the furnace body.
In this second aspect of the present invention, a second feeding chute is installed vertically inside the main feeding chute as a combustion means for shredder dust, and the distal end of the second feeding chute is provided such that a compressed oxidizing gas is blown on the shredder dust that has fallen into the furnace body. Thereby, by increasing the proportion of the oxidizing gas that reaches the shredder dust, the shredder dust does not accumulate and is burnt. Even if it were to accumulate, it would be scattered by the compressed oxidizing gas fed by the second feeding chute, and thus the combustion efficiency is improved.
The second feeding chute may be hung so as to be movable up and down by a wire or the like. In this case, because the second feeding chute is hung such that it can be moved up and down by a wire, the height of the distal end of the second feeding chute from the furnace hearth can be adjusted.
The furnace may comprise a third feeding chute that is provided on one side of the furnace body and feeds compressed oxidizing gas so as to blow on the shredder dust falling into the interior of said furnace body. In this case, because a third feeding chute that blows compressed oxidizing gas to the falling shredder dust is provided on one side of the wall of the furnace body, the combustion efficiency is further improved.
The second feeding chute and the third feeding chute may comprise an iron or stainless steel chute body and a refractory material that covers the periphery of said chute body. In this case, because the structure of the second feeding chute and the third feeding chute has two layers comprising a chute body made of iron or stainless steel and a refractory material covering the periphery of the chute body, its durability is superior.